1. Field of the Invention
The present invention relates to a method for directing an up-shift operation for a vehicle with a manual transmission, or in other words, a method by which a driver of the vehicle is informed of a running condition of the vehicle requiring an up-shift operation.
2. Description of Background Art
In systems for directing an up-shift operation for a vehicle having a manual transmission, a driving condition requiring an up-shift operation is judged by means of the rotational speed of the engine and the gear position, i.e. a result of detection of a currently engaged gear position. A reference speed is previsouly set for each of the gear positions. When the detected vehicle speed exceeds the reference speed corresponding to a detected gear position, an indication device, for example, a lamp is lit up so that a driver of the vehicle is informed that an up-shift operation is needed. However, in conventional systems for directing an up-shifting operation constructed in this way, a drawback has been recognized in that a desirable direction (indication) of up-shift operation is not produced on some occasions, for instance, when the manual transmission of the vehicle is of a normal type having at least three forward gear positions. More specifically, the reference speed for up-shift operation is uniformly determined according to the currently engaged gear position without regard to the degree of acceleration of the vehicle during a preceding up-shift operation. Therefore, under such a condition that the gear has been shifted from a low speed gear to a medium speed gear while the acceleration of the vehicle is not rapid, the direction of up-shift operation may not be produced even though an up-shift operation to a high speed gear is appropriate for fuel economy rather than to keep the currently engaged medium speed gear.
Further, in the operation of a five speed type of transmission, there is a case that an up-shift operation from the third gear is effected while the vehicle is accelerating rapidly, and subsequently cruising of the vehicle at a speed slightly lower than a reference speed for an up-shift operation to the fifth gear is continued. In such a case, it is desirable, in view of the fuel economy reasons, to up-shift the transmission to the fifth gear rather than to keep the cruising state with the fourth gear.